Cannot read property 'props' of undefined?

Question

JavaScript

When entering into a textarea, an error pops up:
Cannot read property 'props' of undefined

class Mes1 extends React.Component{
    constructor(props) {
        super(props)
        this.props = props;
        window.two = props;  // пропсы приходят
    };

    changePostText(e)
    {
        console.log(e.target.value);
        let text = e.target.value;
        this.props.changePostText(text);  // can't read property 'props' of undefined

    }
    render()
    {
        return (
            <div>
                <textarea onChange={this.changePostText} value={this.props.postText} />
            </div>
        )}
}

Answer 1

the this context is lost

changePostText = e => { console.log(this.props) }

// или

onChange={this.changePostText.bind(this)}

https://ru.reactjs.org/docs/faq-functions.html#how...